759 patients with a prosthetic valve replacement (335 mitral prostheses, 184 aortic prostheses and 240 double or triple valve replacements) were regularly followed-up for a total duration of 3 715 patient years. The mean age of these patients was 30 years. 681 (90%) of these patients were treated by long term anticoagulants, which were effective in only 320 patients. 78 patients did not receive anticoagulant treatment. 97 patients presented a total of 129 thrombo-embolic episodes (TEE), i.e. a frequency of 12.7 p. cent or 3.4 embolisms per 100 patients-year. The rate of TEE was influenced by the site of the prosthesis and by the presence or absence of complete arrhythmia due to atrial fibrillation, but it was not influenced by the quality of the anticoagulant treatment. In the patients with a heterograft, the rate of TEE varied according to the site of the prosthesis. In the aortic position, the rate of TEE in our series of prostheses was essentially similar to that reported in series of heterografts by Davila, Oyer and lonescu. This rate is generally higher for the mechanical prostheses in the mitral position and in the case of double valve replacement. The aim of this study was to deduce the current operative indications in relation to the choice of the type of valve replacement.
